Bonking (also known as Metabolic Acidosis)


Mountain biking in Colorado
Mountain biking in the Tarryall Mountains

Ryan had never bonked before, at least in the metabolic shock/ overexertion sense of the word. When he started to bumble around and lose more and more of his edge, I knew that something was up and figured that’s what had happened. Not realizing what was going on, he kept on trying to mountain bike further up the Colorado Trail, although with diminishing returns. The big patches of snow that remained on the trail, even though it was June, were probably a good thing since they ultimately turned us all around. His disrupted mental and physical state likely made the retreat more palatable to the 13-year-old, since he wasn’t one to be prone to turn around before his goal was reached.

I’m sure that there’s some sort of scientific or medical description for just what bonking is, although I never really studied it from a medical standpoint. But, I had experienced it first-hand more than once by the time Ryan was trying to figure out why his heart was beating so fast, and his legs felt like jello. And so I had my suspicions that it might be just that.

The symptoms—weakness, fast heart rate, and disorientation are a bit scary. Thankfully, bonking often rectifies itself eventually, assuming that whatever physical activity caused it in the first place is curtailed. And, it is ultimately less troubling than some other maladies with similar symptoms. But to rush to the bonking conclusion too quickly (and perhaps wrongly) can be dangerous and not something I ever wanted to do. Seeing someone unable to do the physical tasks they usually had no problem accomplishing is disconcerting. But since I’d been in that state myself, as I observed his actions, I was able to predict what he was likely to do next.

By the time he reached full bonk, we were several miles from the trailhead, which was not ideal. But since it was downhill almost all the way back to the van, the stretch of trail that we were on was not physically demanding. And because I was carrying a lot of extra food (a treatment for bonking), I was optimistic about the situation. Besides, there weren’t many other options, other than going back to the start, which we were doing, anyway.

Soon after we turned around, I stopped the group for a short rest and we had some snacks. I got Ryan to eat the rest of the food he was carrying and noted that up to that point, he’d already consumed more than a quart of water. “Good thing,” I concluded, “he’s stayed well hydrated,” and I noted that he still had sufficient water for the rest of the return.

Ultimately, we made it back to the trailhead. Ryan ate a bunch more food and was fully recovered within hours. He’d been introduced to one of the pitfalls of not fueling up enough during significant physical exertion at altitude and likely learned the lesson well.

On the other hand, I had the same thing take place to myself three times through the years and was apparently slower at learning the same lesson. The first time it occurred was mostly because of my ignorance regarding what could happen to a body without proper fuel intake during exertion, like with backpacking, running, or mountain biking. I’m not sure what my thinking was leading up to the second event, but for whatever reason, it just happened. And that takes us to the third time.

Several years after the Ryan event and even several more after my first two, it happened to me again. As the symptoms began to develop, I brushed them off as a manifestation of weakness or lack of physical training. It happened during a long mountain bike group ride in the Colorado mountains, which I’d already done several times previously. I was careful to snack along the way and had a definite idea regarding the route and how it would likely all play out.

My problem in this case was not food, but water. The length of the ride was 5 or 6 hours. While I typically didn’t tend to drink a lot of water while riding, I initially did in this particular case. And by doing so, I stayed well hydrated, at least for a time. Even though the ride was long, I didn’t carry any extra water with me since I knew that there was a Forest Service campground about two-thirds of the way along the route where I could refill.

The group was composed of strong riders, and the pace was consistently fast. By keeping myself well fueled and hydrated, during the initial part of the ride I felt strong and rode mostly in a respectable middle of the group position. About midway through the ride however, and as we began riding the final stretch up to the campground with the supposed water, I polished off the last of my hydration fuel. As I drank the last drop, I confidently started anticipating the long drink that I would take at the campground hand pump as I replenished my empty water bottle. I’d gotten water out of that pump several times during the previous summer and was pleased with myself for coming up with a plan to reduce the weight I was carrying by limiting myself to just one bottle.

I felt strong and was in high spirits as we rode into the Lost Park Campground until I looked at the concrete slab where the hand pump was normally located and saw that it’d been removed for the winter. I was speechless as I tried to think of somewhere else way out there in the boonies that had drinking water. I soon realized that there were no immediate options other than the untreated creek water trickling along nearby. So, I decided to just go the rest of the way without water and be thirsty.

We didn’t even bother to stop at the empty pump foundation as we rode on toward the saddle between Topaz Mountain and North Tarryall Peak. I felt sad and kind of sickened as we passed the place where the water had once been, but within only minutes, became focused on the climb at hand.

I soon began to feel the effects of the lack of water but ignored what my body was telling me. About 15 minutes after passing the campground, the climb to the pass started. I downshifted into successively easier gear combinations as the uphill progressed. As the pedaling became more difficult, my first thought was that I was just in too big or “hard” of a gear and needed to shift into an easier one.

But alas, I eventually got down into my easiest gear combination and, at that point, was barely moving forward. I struggled to stay upright given my slow forward movement, although I was riding along at what I thought to be normal cruising speed. After several riders breezed past me with smiles on their faces and seemingly without undue effort, I finally realized how slow I was actually moving.

Suddenly, it became difficult for me to push the pedals for more than a few seconds at a stretch. My mind told me that it wasn’t all that steep, but my high heart rate and leg weakness each said something else. Within minutes I was bringing up the rear and falling further behind all of the time.

By this point, still almost a half-mile below the top of the pass, I realized that I’d bonked- once again. Had there been any water in a creek or mudpuddle on the ground, I would have gladly drunk it. But there wasn’t, and so that wasn’t even an option. While that fact didn’t help my bonk situation, it more than likely saved me from other, potentially compounding intestinal ones.

Up to this point, I was just one of the riders in the group. But suddenly, a sort of “group dynamic” pressure developed in my own mind. I began to struggle just to ride and realized that the others were ahead and would likely be waiting for me. What was usually a leisurely fifteen-minute ride from there to the top became an inconceivable concept.

I continued riding, even though I was only moving a few feet forward every minute or so. Because of the ridiculously slow pace, my greatest struggle was in keeping myself upright. Walking and pushing my bike would be faster, I realized. But my mind-fog prevented me from doing that as I decided that would be an ultimate humiliation. Of course, I didn’t consider how pitiful I looked as I wobbled/rode along at less than a mile an hour.

After what seemed like hours of climbing, the trail emptied me into an open and previously logged area. I blurrily saw the group waiting for me at the far end of a clearing. They were barely a hundred yards ahead, and I attempted to look normal as I rode the last bit toward them. In reality, there was no doubt that things were not going  well for me in anyone’s mind.

Eventually, I did reach them. The thing that riders sometimes do in such a situation is to declare a “mechanical problem” that set you back. But that was too complicated for me to figure out, and I just said that I was feeling a bit off, but was getting better. There were various food and water offers, but I turned them all down, saying (and lying) that I had plenty of each.

I knew that the top of the pass was not much further. I reasoned that once I got up to that point, it would be smooth sailing from there back to my Tarryall mountain Base Camp since it was mostly downhill. The ride from there on up to the top was not as pleasant as I outwardly tried to make it appear, but within a few minutes, we were all cresting the pass, and the downhill began.

It was a fast and painless descent for the others, but a slow and deliberate one for me as I rode at the back. While my speed (or lack of it) made the riding part reasonably doable, it also took me out of the route finding aspect. That fact typically wouldn’t be a problem, except that in this case, the trail we were following was somewhat vague, and I was the only one in the group who had any clue about where it actually went. In addition to my bike riding worries, at that point, I also became the supposed route finder.

My friend Tom was riding at the front. As we neared the bottom, I helplessly watched from behind as he made a wrong turn. Immediately, I sped up and began yelling for everyone to stop. They all did, except for him, since he was too far gone. Realizing that I needed to catch him, an adrenaline rush thankfully sped me up. Somehow, I passed the stopped riders without crashing and yelled at them to proceed straight across the creek rather than following Tom and then just work their way on back to the camp. I also let them know that I would go get Tom, and we’d then ride on down to the main road. Then, once they got back to the camp, one of them should drive down the road and pick us up. And so, they rode off in one direction as I continued in another.

I continued on and finally did catch up to Tom, who was waiting at a creek crossing. I quickly gave him an abridged explanation of what had happened. Then, the two of us went on across the creek and began riding down a two-track dirt road that we assumed would painlessly take us on to the main road. Our plan was to get to the road and just wait there for one of the others to pick us up and shuttle us back to the camp. It seemed simple enough, assuming that the road did what we thought it would do. But alas, it didn’t.

Riding the two-track road was pleasant, for a time, as it continued effortlessly descending toward the paved county road, some three miles off in the distance. I was thankful for the smooth and easy riding as we quickly covered two or so of those miles. All was good, and I was confident that I could at least keep coasting and rolling downward until we came to a surprise uphill.

I was a bit disheartened to see and feel the road do what it did. But I assumed the uphill would be short, and so “attacked” the climb. My legs felt strong for the first couple of seconds of the ascent. But the next five minutes that it took to ride 100 feet were painful as my muscle-memory quickly remembered what’d been going on with my body less than an hour before. I would’ve cried, but I didn’t have enough fluid in my tear ducts to do so.

After a while, we did get to the summit of what I hoped was the final hill. We stopped, took a break, and thankfully saw the main road in the distance and down below. By this time, reaching the Tarryall Road had become my sole mission in life. All I wanted to do was get down to it and hoped that when I did, one of the others would actually show up to drive me home.

Even though I didn’t want to admit it to myself, I knew that regardless of what happened at the main road, I didn’t have enough fuel left in my system for riding all the way back to the lodge. So assuming I did get down there I would either sit on the side of the road or get the ride.

We finally did make it down to the pavement, and after only a short wait, one of the others showed up in his car to take me back to the lodge. There wasn’t space for my bike, so I just stuck it behind a bush and crawled into the passenger seat. I planned to return and retrieve it later that day, although, at the time, I didn’t even care about whether or not it was safe where I left it.

Once back at the camp lodge and after drinking three bottles of water, I began to regain my senses. When I regained my coherence, I began to wonder about how the others had ever found their way back to the lodge and started worrying about my bike. After an hour of small talk and good-byes, everyone left, and I drove off in my pickup to get the bike.

When I got to where I’d left it, I was thankful to see it was still there. So, in the end, I didn’t lose much during the ordeal other than several pounds of water weight. And, as a bonus, I once again learned the bonking lesson. But it was then that I finally embraced the importance of staying well fueled and hydrated. I also definitively came to understand the pitfalls of assumption. And once and for all, I recognized the benefits of being well prepared.

A blurry picture of a mountain biker riding through the woods
Dream time on a bike

Author: David Appleton

I was born and raised in Texas and currently live in the Texas Hill Country, spent some 30 years living in the smack dab middle of Colorado, and have spent a lifetime adventuring and leading others on adventures in many parts of the wild world.

%d bloggers like this: